Display device having sealing grooves

ABSTRACT

A display device includes: a resin layer on the circuit layer including a groove surrounding and separating a display area; light-emitting elements on an upper surface of the resin layer so as to emit light with luminances controlled by the currents; a sealing layer covering the light-emitting elements; a second substrate above the sealing layer; a sealing material provided between the sealing layer and the second substrate so as to surround the display area and the groove; and a filling layer surrounded by the sealing material between the sealing layer and the second substrate. The groove is formed along a line describing a shape that is inscribed in a rectangle and not in contact with corners of the rectangle as viewed in a direction vertical to the upper surface of the resin layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/428,254 filed on May 31, 2019, which, in turn, is a continuation of U.S. patent application Ser. No. 16/166,861 (now U.S. Pat. No. 10,355,238) filed on Oct. 22, 2018, which, in turn, is a continuation of U.S. patent application Ser. No. 15/964,405 (now U.S. Pat. No. 10,141,539) filed on Apr. 27, 2018, which, in turn, is a continuation of U.S. patent application Ser. No. 15/205,142 (now U.S. Pat. No. 10,003,045) filed on Jul. 8, 2016. Further, this application claims priority from Japanese Application JP2015-139217 filed on Jul. 10, 2015, the entire contents of which are hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a display device in which a light-emitting element that is an electroluminescence (EL) element, an organic EL element, or other self-luminous type display element is mounted.

2. Description of the Related Art

In a display device in which a plurality of light-emitting elements represented by organic EL elements or the like are disposed, a display area is covered by a sealing layer configured of a silicon nitride film or the like in order to prevent the degradation of the organic EL elements due to moisture entering the interior of the display device.

In JP 2008-186681 A, it is described to provide a highly reliable organic EL display device capable of preventing degradation due to the influence of moisture. Especially in FIG. 2, an invention is disclosed in which, by coating a coating-type moisture absorbent in a direction away from a corner portion of the display area, moisture or the like is prevented from entering from the corner portion of the display area. When the coating-type moisture absorbent is coated in the direction away from the corner portion as described above, there is a problem in that a picture-frame area is increased.

Here, even when the light-emitting elements in the display area are protected by the sealing layer, adverse effects due to the entry of moisture may occur.

A path for moisture to the display area protected by the sealing layer is assumed to be formed in a planarizing layer formed of an organic insulating film for planarizing irregularities caused by a circuit layer or in a pixel separation film formed of an organic insulating film for separating the light-emitting elements for each pixel.

SUMMARY OF THE INVENTION

In view of the problems described above, it is an object of the invention to provide a display device in which the entry of moisture into a display area where a plurality of light-emitting elements are disposed is prevented.

A display device according to an aspect of the invention includes: a first substrate; a circuit layer formed on the first substrate so as to include circuits for controlling currents respectively corresponding to a plurality of unit pixels constituting an image; a resin layer provided on the circuit layer and including a groove surrounding and separating a display area; a plurality of light-emitting elements provided on an upper surface of the resin layer so as to emit light with luminances controlled by the currents; a sealing layer covering the plurality of light-emitting elements; a second substrate disposed above the sealing layer; a sealing material provided between the sealing layer and the second substrate so as to surround the display area and the groove; and a filling layer surrounded by the sealing material between the sealing layer and the second substrate, wherein the groove is formed along a line describing a shape that is inscribed in a rectangle and not in contact with corners of the rectangle as viewed in a direction vertical to the upper surface of the resin layer.

A display device according to another aspect of the invention includes: a first substrate; a circuit layer formed on the first substrate so as to include circuits for controlling currents respectively corresponding to a plurality of unit pixels constituting an image; a resin layer provided on the circuit layer and including a groove surrounding and separating a display area; a plurality of light-emitting elements provided on an upper surface of the resin layer so as to emit light with luminances controlled by the currents; a sealing layer covering the plurality of light-emitting elements; a second substrate having a planar shape smaller than that of the first substrate and disposed above the sealing layer so as to expose a portion of the first substrate; a sealing material provided between the sealing layer and the second substrate so as to surround the display area and the groove; and a filling layer surrounded by the sealing material between the sealing layer and the second substrate, wherein the planar shape of the second substrate includes corner portions that are inscribed in a rectangle and coincident with or inside corners of the rectangle, and the groove is formed along a line describing a similar figure obtained by reducing a shape that is inscribed in the planar shape of the second substrate and not in contact with the corner portions as viewed in a direction vertical to the upper surface of the resin layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an organic EL display device according to a first embodiment.

FIG. 2 is a schematic view showing the state of a pixel circuit of the organic EL display device in the first embodiment.

FIG. 3 is a cross-sectional view for explaining the state of a pixel of the organic EL display device in the first embodiment.

FIG. 4 is a cross-sectional view for explaining the state of a picture-frame area located around the periphery of a display area and the state of a terminal portion of the organic EL display device in the first embodiment.

FIG. 5A is a plan view showing the state of the vicinity of corner portions of the display area in the first embodiment.

FIG. 5B is an enlarged plan view showing the state of the vicinity of one corner portion of the display area in the first embodiment.

FIG. 5C is an enlarged plan view showing the state of the vicinity of one corner portion of the display area in the first embodiment.

FIG. 6 is a diagram showing the state of a cross-section along VI-VI in FIG. 5A.

FIG. 7 is a diagram showing Modified Example 1 of the organic EL display device in the first embodiment.

FIG. 8 is a diagram showing Modified Example 2 of the organic EL display device in the first embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an organic EL display device according to each embodiment of the invention will be described with reference to the drawings.

First Embodiment

FIG. 11 is a schematic plan view for explaining an organic EL display device 1 of a first embodiment. The organic EL display device 1 of the embodiment is configured by bonding a second substrate B2 to a first substrate B1 on which organic electroluminescence elements as a plurality of light-emitting elements are disposed. In an area (exposed area EX) of the first substrate B1 exposed from the second substrate B2, a driver semiconductor device IC for driving the organic EL display device 1 is disposed. Further, a flexible printed board FPC is disposed in the vicinity of the edge portion of the exposed area EX of the first substrate B1.

FIG. 2 is a diagram showing the state of a pixel circuit in a display area DP of the organic EL display device 1 of the first embodiment. The organic EL display device 1 includes the display area DP where an image is displayed, a scanning signal line drive portion GDR, a video signal line drive portion DDR, and a power source drive portion EDR.

In the display area DP, organic electroluminescence elements OL and pixel circuits PX are disposed in a matrix corresponding respectively to a plurality of pixels. The pixel circuit PX is configured of a thin film transistor TFT1, a capacitive element CAP, and a thin film transistor TFT2. The scanning signal line drive portion GDR, the video signal line drive portion DDR, and the power source drive portion EDR drive the pixel circuit PX to control light emission of the organic electroluminescence element OL.

The scanning signal line drive portion GDR is connected to scanning signal lines GL each provided for an array of pixels (pixel row) in the horizontal direction, and outputs a scanning signal to the scanning signal lines GL sequentially selected.

The video signal line drive portion DDR is connected to video signal lines DL each provided for an array of pixels (pixel column) in the vertical direction, and outputs, in synchronization with the selection of the scanning signal line GL by the scanning signal line drive portion GDR, a voltage in response to a video signal of the selected pixel row to each of the video signal lines DL. The voltage is written to a capacitor in the pixel circuit PX, and a current in response to the written voltage is supplied to the organic electroluminescence element OL.

The power source drive portion EDR is connected to drive power source lines SL each provided for the pixel column, and supplies a current to the organic electroluminescence element OL through a switching element in the pixel circuit PX.

A cathode of the organic electroluminescence element OL is connected to a ground potential, and the cathodes of the organic electroluminescence elements OL of all of the pixels are configured of a common electrode.

FIG. 3 is a diagram for explaining the state of a cross-section of a unit pixel in the organic EL display device 1 of the first embodiment. As shown in the drawing, the organic EL display device 1 is configured to include the first substrate B1 on which the plurality of organic electroluminescence elements OL are formed, the second substrate B2 which is disposed to face the first substrate B1 and on which a color filter layer CF and a black matrix BM are formed, and a filling layer FL filled between the first substrate B1 and the second substrate B2.

Moreover, the organic electroluminescence element OL is configured to include a pixel electrode P1, an organic layer E1, and a common electrode C1, in which the pixel electrode P1 and the organic layer E1 are in contact with each other and the organic layer E1 and the common electrode C1 are in contact with each other. A wiring layer L1 for forming the capacitive element CAP between the pixel electrode P1 and the wiring layer L1, and a capacitive insulating layer CP are disposed. The capacitive insulating layer CP is formed of an inorganic insulating film such as, for example, silicon nitride (SiNx). Moreover, a planarizing layer (resin layer) HPL formed of an organic insulating film such as acrylic resin or polyimide resin is formed for a base of the organic electroluminescence element OL, and the pixels (the organic electroluminescence elements OL) are separated from each other by a bank layer (resin layer) BNK formed of a similar organic insulating film.

The pixel electrode P1 (anode) of the organic electroluminescence element OL is formed of high-reflective metal such as aluminum, and extends to the bottom portion of a contact hole CH to be connected to a transparent conductive layer T1. The pixel electrode P1 is electrically continuous with a source electrode of the thin film transistor (TFT) formed below the planarizing layer HPL. The common electrode C1 is formed of a transparent conductive film such as indium tin oxide (ITO), and serves as one layer of solid-like electrode common to all of the pixels in the display area DP.

The organic layer E1 in the embodiment is formed between the common electrode C1 and the pixel electrode P1, and configured to include a hole transport layer, a light-emitting layer, and an electron transport layer. In the light-emitting layer in the organic layer E1, holes injected from the pixel electrode P1 and electrons injected from the common electrode C1 are recombined to emit light. All of the layers constituting the organic layer E1 may be formed over the entire display area DP, or may be formed individually for each of the pixel. The luminance of the light-emitting layer of the organic electroluminescence element OL is controlled by a current from a circuit layer CL. The circuit layer CL includes the thin film transistor TFT2 and the thin film transistor TFT1 (not shown).

Moreover, the organic electroluminescence elements OL of the pixels are covered and protected by a sealing layer PR. The sealing layer PR in the embodiment is configured of an inorganic insulating film, and specifically, configured to include a silicon nitride layer and a silicon oxide layer. The sealing layer PR may include, for example, a resin layer interposed partially between the silicon nitride layer and the silicon oxide layer, or an organic insulating film may be included in a portion of the sealing layer PR in some cases.

The planarizing layer HPL is formed of an organic insulating film to a relatively thick thickness, and absorbs steps produced on the circuit layer CL in which the thin film transistor TFT and the like are formed, and planarizes the circuit layer CL. As shown in the drawing, the circuit layer CL is configured to include the electrodes of the thin film transistor connected to the pixel electrode P1, other wirings, a gate insulating film, and an inter-layer insulating film, and includes circuits for controlling currents respectively corresponding to the pixels in the display area DP.

FIG. 4 is a diagram showing the state of a picture-frame area located around the periphery of the display area DP and the state of a terminal portion TE formed in the exposed area EX of the organic EL display device 1 in the first embodiment. The left figure in FIG. 4 shows the state of the picture-frame area, while the right figure shows the state of the terminal portion TE. A sealing material DM that bonds the first substrate B1 and the second substrate B2 together is provided therebetween. The sealing material DM is disposed along the outline of the second substrate B2, and the filling layer FL is disposed inside the sealing material DM.

As shown in the left cross-sectional view in FIG. 4, the common electrode C1 is in contact with the transparent conductive film T1 exposed in the picture-frame area (outside the display area DP), and is supplied with a common potential through the wiring layer L1. As shown in the right cross-sectional view in FIG. 4, a metal layer in the same layer as the source/drain electrode of the thin film transistor is exposed in the terminal portion TE, and connected from the terminal portion TE to the driver semiconductor device IC.

Here, especially FIG. 5A shows a schematic view when the first substrate B1 of the organic EL display device 1 in the embodiment is viewed from above. As shown in the drawing, a groove GR1 (first groove) for blocking the entry of moisture from the planarizing layer HPL and the bank layer BNK both formed of an organic insulating film is disposed between the display area DP where an image is displayed and an area where the sealing material DM is disposed. FIGS. 5B and 5C are diagrams each showing an enlarged view of a corner portion at the upper right portion of the organic EL display device 1, in which representation of a groove GR2 (second groove) is omitted.

The sealing material DM has a rounded shape at the corner portions of the second substrate B2 bonded to the first substrate B1, and includes curved portions CV each of which is concave in a direction in which the corner portion of the display area DP projects. The groove GR1 is configured in such a shape to avoid overlapping with the sealing material DM because an entry path for moisture to the display area DP may be formed when the groove GR1 overlaps the sealing material DM. That is, as viewed planarly, the groove GR1 is formed, as shown in FIGS. 5A and 5B, so as to be inscribed in a rectangle RC surrounding the display area DP, and formed, at the portions of corners of the rectangle, along a line describing a shape that is not in contact with the corners.

From another point of view, as shown in FIG. 5C (representation of the groove GR2 is omitted in FIG. 5C), the groove GR1 is formed along a line describing a similar figure SH1 to a shape SH that is inscribed in the planar shape of the second substrate B2 and not in contact with the corner portions of the second substrate B2, and formed to be smaller than the shape SH.

Specifically, the groove GR1 in the embodiment extends in a straight line in an oblique direction inside the corners of the rectangle RC surrounding the display area DP to connect the groove GR1 that extends in the vertical direction with the groove GR1 that extends in the horizontal direction, and thus the groove GR1 depicts chamfered corners with the vertices of the rectangle of the display area DP removed.

Although, in FIG. 5A, the groove GR2 is also formed at a position overlapping the sealing material DM, the groove GR2 may not be necessarily present in terms of blocking moisture.

FIG. 6 is a diagram showing a cross-section along VI-VI in FIG. 5A. As shown in the drawing, the groove GR1 is formed by removing the planarizing layer HPL and the bank layer BNK by etching. As described above, the groove GR1 divides the resin layers into the resin layers on the display area DP side and the resin layers on the sealing material DM side.

As the groove GR1 in the embodiment, first, an outer tapered shape GRa is formed in the planarizing layer HPL that is located around the periphery of the display area DP and located in the picture-frame area. Further, the capacitive insulating layer CP is formed on the surface of the tapered shape GRa, so that the organic insulating film due to the planarizing layer HPL is divided by the inorganic insulating film. Next, the bank layer BNK is formed so as to be filled in the tapered shape GRa covered by the capacitive insulating layer CP, and thereafter, an inner tapered shape GRb is further formed. The common electrode C1 is formed on the surface of the inner tapered shape GRb, and further, the sealing layer PR is filled inside the tapered shape GRb.

Hence, in the groove GR1, the organic insulating films of the bank layer BNK and the planarizing layer HPL are divided by the sealing layer PR and the common electrode C1, and further, the organic insulating film of the planarizing layer HPL is divided by the capacitive insulating film CP. With the groove GR1 described above, a moisture path that may be formed in the bank layer BNK or the planarizing layer HPL is divided, so that moisture is prevented from reaching the organic layer E1 formed in the display area DP and thus the reliability of the organic EL display device 1 is improved.

In the embodiment as described above, the groove GR1 is configured of the outer tapered shape GRa and the inner tapered shape GRb in the planarizing layer HPL. However, it is sufficient that the groove GR1 penetrates the organic insulating films of the planarizing layer HPL and the like so as to reach the inorganic insulating film located on the uppermost surface of the circuit layer CL and in contact with the lower surface of the planarizing layer HPL and, further, the planarizing layer HPL on the display area DP side and the planarizing layer HPL on the outside thereof are divided with the inorganic insulating film that intervenes therebetween.

Moreover, the groove GR2 surrounds the groove GR1 from the outside, and is formed into a rectangular shape. However, since the groove GR2 is formed at the position overlapping the sealing material DM, there is a risk that the sealing layer PR and the like within the groove GR1 may be broken by spacer particles SP that are contained in the sealing material DM and define a gap between the first substrate B1 and the second substrate B2. For this reason, there is a possibility that an entry path for moisture is formed in the groove GR2, so that the groove GR2 alone cannot sufficiently prevent the entry of moisture into the display area DP.

Moreover, when the groove GR1 is formed angular without removing the vertices of the rectangular shape similarly to the planar shape of the groove GR2, there is a possibility that the rounded curved portion CV of the sealing material DM may overlap the groove GR1 at the position of the corner of the groove GR1 due to a slight shift in the disposition of the sealing material DM. As described above, when the overlapping of the sealing material DM and the groove GR1 occurs, there is the risk that the sealing layer PR may be broken by the spacer particles SP contained in the sealing material DM and thus the entry path for moisture may be produced. Therefore, by forming the groove GR1 with a rectangular planar shape with the vertices removed as in the embodiment, the entry of moisture can be prevented while reducing alignment accuracy for disposing the sealing material DM. Further, since there is no need to coat a coating pattern of the sealing material DM in an outward convex shape so as to avoid the corner portion of the groove GR1, the picture-frame area can be narrowed.

Next, FIG. 7 is a diagram showing Modified Example 1 of the organic EL display device 1 of the first embodiment. As shown in the drawing, the planar shape of the groove GR1 is formed so as to be inscribed in the top, bottom, left, and right sides of the rectangle RC surrounding the display area DP, while extending, inside the corners of the rectangle RC, in a curved line that is convex in the projecting direction of the corners. Specifically, the groove GR1 of Modified Example 1 has a rounded shape inside the corners surrounding the display area DP. The curvature of the corner portion in the groove GR1 may be larger than the curvature of the corner portion of the sealing material DM.

By forming the corner portions in the groove GR1 into a rounded shape as described above, a stress is prevented from concentrating on the sealing layer PR and the like filled in the groove GR1, and thus the breakage of the sealing layer PR at the corner portion is prevented. The overlapping of the sealing material DM and the groove GR1 can also be prevented, and thus the breakage of the sealing layer PR at the corner portion is prevented.

FIG. 8 is a diagram showing Modified Example 2 of the organic EL display device 1 of the first embodiment. As shown in the drawing, grooves GR3 (third grooves) that couple the groove GR1 disposed inside the sealing material DM with the groove GR2 disposed overlapping the sealing material DM are formed in Modified Example 2. The grooves GR3 are formed while avoiding the corner portions of the groove GR2 and the like, so that even when moisture enters the corner portion of the groove GR1, the moisture is prevented from traveling to the sides connected to the corner portion of the groove GR1.

Although, in the embodiment described above, the inorganic insulating film or the metal layer other than the sealing layer PR is also formed inside the groove GR1, the inorganic insulating film or the like other than the sealing layer PR may not be included for example. Moreover, the sealing layer PR may be configured of a single layer of inorganic insulating layer, or may be configured of a plurality of different kinds of inorganic insulating layers.

The display device in the embodiment described above is the organic EL display device 1, but is not limited to an organic EL display device as long as it is a display device. The display device may be a display device including a light-emitting element such as a quantum-dot light-emitting diode (QLED) in each pixel.

While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention. 

What is claimed is:
 1. A display device having a display region, the display device comprising: a first substrate having an insulating surface; a circuit layer on the insulating surface, the circuit layer having a pixel circuit in the display region; a first insulating layer covering the circuit layer, the first insulating layer having a first slit and a second slit; a pixel electrode on the first insulating layer, the pixel electrode being connected to the pixel circuit; and a second insulating layer on the first insulating layer and on part of the pixel electrode, the second insulating layer having a third slit and a fourth slit wherein the first slit surrounds the display region in a plan view, the second slit surrounds the display region, the first slit is between the display region and the second slit in the plan view, the third slit overlaps with the first slit and inside the first slit, the fourth slit overlaps with the second slit and inside the second slit, and both edges of the first slit and both edges of the second slit are covered with the second insulating layer.
 2. The display device according to claim 1, further comprising a light emitting element, wherein the light emitting element includes the pixel electrode, a common electrode, and an organic layer including a light emitting material between the pixel electrode and the common electrode, and the second insulating layer covers an edge of the pixel electrode and exposes a part of an upper surface of the pixel electrode.
 3. The display device according to claim 2, wherein the common electrode covers the pixel electrode, the organic layer, the first slit, and the third slit, and the common electrode does not cover the second slit and the fourth slit.
 4. The display device according to claim 1, further comprising a sealing layer, wherein the sealing layer covers the display region, the first slit, the second slit, the third slit, and the fourth slit continuously.
 5. The display device according to claim 1, wherein each of the first insulating layer and the second insulating layer comprises an organic insulating material.
 6. The display device according to claim 4, wherein the sealing layer comprises an inorganic insulating material including silicon nitride.
 7. The display device according to claim 1, further comprising: a second substrate; and a sealing material between the first substrate and the second substrate, wherein the sealing material surrounds the display region in the plan view, the sealing material covers the second slit and the fourth slit, and the sealing material does not cover the first slit and the third slit.
 8. The display device according to claim 1, further comprising: a second substrate; and a filling material between the first substrate and the second substrate, wherein the filling material covers the display region, the first slit, and the third slit. 